This invention generally relates to a pump and valve assembly for inflating a prosthesis. More particularly, the invention relates to pressure based mechanisms that inhibit spontaneous inflation of the prosthesis, including stiffening and support mechanisms that also improve the function of the valve.
One common treatment for male erectile dysfunction is the implantation of a penile prosthesis. Such a prosthesis typically includes a pair of inflatable cylinders which are fluidly connected to a fluid (typically liquid) reservoir via a pump and valve assembly. The two cylinders are normally implanted into the corpus cavernosae of the patient and the reservoir is typically implanted in the patient's abdomen. The pump assembly is implanted in the scrotum. During use, the patient actuates the pump and fluid is transferred from the reservoir through the pump and into the cylinders. This results in the inflation of the cylinders and thereby produces the desired penis rigidity for a normal erection. Then, when the patient desires to deflate the cylinders, a valve assembly within the pump is actuated in a manner such that the fluid in the cylinders is released back into the reservoir. This deflation then returns the penis to a flaccid state.
With inflatable penile prostheses of current designs, spontaneous inflation of the cylinders is known to occasionally occur due to inadvertent compression of the reservoir, resulting in the undesired introduction of fluid into the cylinders. Such inadvertent inflation can be uncomfortable and embarrassing for the patient. This undesirable condition is further described below with reference to a particular prosthetic design.
With reference to FIG. 1, a known pump and valve assembly 8 for use in a penile prosthesis includes a fluid input 10 that is coupled at one end to a reservoir (not shown) and to a housing 12 at its opposite end. Also connected to the housing 12 is a fluid output 14 which, in turn, is connected at its other end to a pair of cylinders (not shown). Linking the fluid input 10 and the fluid output 14 to each other is a common passageway 33, which itself contains a valve assembly that is described in greater detail below. Common passageway 33 is also in fluid communication with a pump bulb 18 that is used to move fluid from the reservoir (not shown) to the cylinders (not shown) in order to inflate the cylinders. The valve assembly located within common passageway 33 includes a reservoir poppet 20 which is biased against a valve seat 24 by a spring 28 and a cylinder poppet 22 which is biased against a valve seat 26 by a spring 30. The springs 28 and 30 are sized so as to keep the reservoir poppet 20 and the cylinder poppet 22 biased against each respective valve seat 24 and 26 under the loads that are encountered when the reservoir is pressurized to typical abdominal pressures.
When the patient wishes to inflate the cylinders, pump bulb 18 is squeezed so as to force fluid from the pump bulb 18 into the common passageway 33. The resulting fluid flow serves to reinforce the force from the spring 28 urging the reservoir poppet 20 against valve seat 24 while at the same time causing compression of the spring 30, and thereby opening cylinder poppet 22. As a result, the fluid travels out through fluid output 14 and into the respective cylinders.
When the patient releases the pump bulb 18 a vacuum is created, thus pulling the poppet 22 back against valve seat 26 (aided by spring 30) and simultaneously pulling the reservoir poppet 20 away from its valve seat 24, against the spring 28. As a result, fluid from the reservoir is thus allowed to flow through the fluid input 10 and into the common passageway 33 passing around the reservoir poppet 20 and into the vacuous pump bulb 18. Once the pump bulb 18 has been filled, the negative pressure is eliminated and the reservoir poppet 20 returns to its normal position. This pumping action of the pump bulb 18 and valve assembly is repeated until the cylinders are fully inflated.
To deflate the cylinders, the patient grips the housing 12 and compresses it along the axis of reservoir poppet 20 and cylinder poppet 22 in a manner such that the wall 13 of the housing 12 contacts the protruding end 21 of the reservoir poppet 20 and forces the reservoir poppet 20 away from valve seat 24. This movement, in turn, causes the reservoir poppet 20 to contact cylinder poppet 22 and force cylinder poppet 22 away from valve seat 26. As a result, both poppets 20 and 22 are moved away from their valve seats 24 and 26 and fluid moves out of the cylinders, through the fluid output 14, through common passageway 33, through the fluid input 10 and back into the reservoir.
Although the springs 28 and 30 are sized to provide sufficient tension to keep poppets 20 and 22 firmly abutted against valve seats 24 and 26 under normal reservoir pressures, it is possible that pressure that exceeds the force provided by the springs could be exerted upon the reservoir during heightened physical activity or movement by the patient. Such excessive pressure on the reservoir may overcome the resistance of the spring-biased poppets 20 and 22 and thereby cause a spontaneous inflation of the cylinders. After implantation, encapsulation or calcification of the reservoir may occur. Encapsulation or calcification of the reservoir can lead to additional problems. In particular, the encapsulation could lead to a more snugly enclosed reservoir, thus increasing the likelihood of spontaneous inflation.
In previous attempts to reduce or eliminate the occurrence of spontaneous inflation, different types of spontaneous inflation preventing valves have been introduced into the pump and valve assembly. Such previous valves are intended to permit the positive flow of fluid to the cylinders only in those circumstances when the patient has forcibly manipulated the valve.
Although such previous valve designs reduce the frequency of spontaneous inflation, several drawbacks do exist. For example, such valves are typically complex, requiring two-handed operation which is a serious drawback to elderly or severely ill patients. Some spontaneous inflation preventing valves also require the application of excessive force in order to manipulate the valves; which may be too demanding for some patients. Furthermore, such valve designs may cause patient discomfort due to the valve size or shape, because of increase in the overall volume of the implant within the patient. This increased size can also lead to interference with the patient's normal bodily functions. Such previous valve designs typically add undesirable cost to the device as well as increase the complexity of the surgical implantation procedure.
A solution to the above-identified drawbacks is disclosed in co-pending U.S. patent application Ser. No. 09/749,292 entitled “PRESSURE BASED SPONTANEOUS INFLATION INHIBITOR” which is assigned to the Assignee of the present invention and is incorporated herein by reference. However, the operational efficiency of the prosthesis pump could be further improved by optimizing the operative manipulation of the assembly.
Presently, the pump and valve assemblies used in implantable prostheses share certain characteristics. A compressible pump bulb is attached to the housing and is in fluid communication with the various fluid pathways. In order to inflate the cylinders, the compressible pump bulb is actuated by the patient, thereby urging fluid past the poppets into the cylinders. In order to deflate the cylinders, the valve housing is grasped and squeezed (through the patient's tissue), causing the poppets to unseat and allow fluid to flow back to the reservoir.
Since the pump and valve assembly is positioned within the patient's scrotum, the various components of the assembly must be small. As a result, manipulation of the pump and valve assembly is sometimes difficult. For example, patients requiring the use of a penile prosthesis are oftentimes elderly and have a reduced dexterity as a result of aging. Thus, in some instances, even locating the device within the tissue can be a challenge, let alone identifying the correct portion of the assembly to actuate. More specifically, with some patients it may be difficult to determine whether the housing portion of the assembly that leads to release or deflation of the cylinders is being grasped, or whether the bulb portion which would be used to inflate the cylinders is being grasped.
Notably, the length of the valve assembly is determined (at least in one direction) by the size of the various poppets and the distance such poppets must move in order to open and close the various fluid passageways. As a result, such a pump and valve assembly typically is longer in a direction parallel with the poppets. Moreover, in order to release the poppets in an assembly configured in this manner, the patient must grasp the narrower, shorter sidewalls of the assembly and compresses them together. Such a configuration can present challenges insofar as the spring tension of the poppets at the time of desired deflation is typically at a maximum while the surface area of the assembly which must be compressed in order to cause such deflation is at a minimum. This condition can lead to a situation where the patient has difficulty actually compressing the assembly, or in extreme circumstances, actually loses grip of the assembly during such attempts at deflation.
There exists a need for an improved prosthetic penile implant having a spontaneous inflation prevention mechanism that affords convenient operative manipulation by a patient.